And samuel tiiomp



(No Model.)

W. DIXON S. THOVSGN.

PISTON FOR STEAM ENGNES.

ATTRNEYS.

Unirse v Sintes Arent TILLlABl DIXON, OF SHEFFIELD, COUNTY OF YORK, AND SAMUEL THOBIR SON, OF TRET, COUNTY OF STAFFORD, ASSIGNO AND SAMTEL THOMPSON, BOTH OF HANLF AND THOHAS MUN FAYl-LT.. OF l-`."l` URlA, ENGLAND.

RS TO TOM THOMPSON PISTON FOR STAVlNGlNES.

lPECIEICATION forming part of Letters Patent No. 362,729, dated May 10.11887.

Application filed m'ember 16, 1836. Serial No. 219,024.

To @ZZ whom, it may concern:

Be it known that we, XYXLLIAM DIXON, of Sheffield, in the county of York, England, and Sturm-n. Tnonrsox, of Trent, in the county of Stafford, England, subjects of the Queen of Great Britain, have invented certain new and useful Improvements in Pistons, of which the following is a full, clear, and exact description.

rllhe in vent-ion relates to that class of pistons ro wherein provision is made for the automatic expansion of tlnpackingrings to compensate foi-wear, so that the entire sectional area of the cylinder to which the piston is fitted will always be occupiedvbyllre piston; andthe objectof the invention is to improve the construction of pistons of this character.

rllhe invention consstsin the means substantially as hereinafter described and claimed.

Reference is to be .had to the accompanying zo drawings, forming part of this specification,

in which similar letters of reference indicatev corresponding parts in all the iigures.

Figure l is a central sectional elevation of a piston embodying our invention. Fig. 2 is a face view of the same, partly in section; and

Fig. 3 is an edge view ofthe same.

The body a ol the pist-on is formed with a series of recesses or pockets, b, extending radially from near the center to the periphery,

3o for the reception of blocks or studs d, the said studs or blocks being provided on the Shanks at their inner ends with spiral or other suitable springs, c, for the purpose presently to be explained. In a groove in the periphery by the outer ends of the blocks or studs d, is placed Athe ring f, reverscly beveled onits outer surface and made preferably in segments, as shown at i, Fig. 2. The said peripheral groove is formed by the annular rim or raised portion g of the piston and the clamping plate or cap h. In this peripheral groove, also, and abutting the side walls thereof, are the packing-rings e e, of suitable material,

which project beyond the periphery of the bodyof the piston, asshown, and againstwhich bears the lspring-pressed segmental ring f, their inner edges, where they adjoin the ring of the piston, and resting on and supported (No model.) P/ntcn'rell in England May 8, 1886, No. 6,227.

f, bein-g beveled correspondingly tothe wedge shape ofthe said ring f. XVith this construc- 5o tion, it is evident that as the pressure ol" the springs c forces the blocks or studs al outward, and with them the ring f, the latter will, by reason of its wedge shape, force the packing rings c e outward against the cylinder or case to which it is fitted, and also wedge the same laterally against the opposite walls of the peripheral groove, insuring a tight iit of the piston in the engine or other cylinder to which it is applied, and effectually preventing the 6o entrance of steam behind'the packing-rings, and the eousmiprent deleterious elfeets should the steam effect an entrance to the parts behind the said packing-rings. lt will be 0bserved, also, that by the invention above described a space is formed on the periphery at either side ol' the packing-rings, wherein the steam or other mtive agent may circulate, forming a cushion therein, and thus exerting the same pressure on the face and-around the 7o peripheral edge of the piston. A very desirable reduction ol' the frietional surface is also elfccted by this forni of piston.

By means of the blocks interposed between the packing-rings and springs the latter are caused to exert a direct and even pressure.

The nu mber of springpressed studs or blocks d will vary according to the diameter of t-he piston and the strength of the springs employed;or the blocks d maybe dispensed with 8o entirely and a direct pressure on the segmental ringf providedl'or by extending the springs outward to the said ring, 'or in any other suitable manner.

It will be understood that this invention is adapted to pumps and valves as well as to engine-cylinders, and that it is notlimted to the precise construction and arrangement of parts `shown.

Having thus described our invention, we 9o claim as new and desire to secure by Letters lPatent-fb 1. A piston provided in a peripheral groove thereof with packing-rings, a reversely-bevf eled ring behind and bearing against said '95 packing-rings, and spring-pressed blocks behind the said reversely-bevelcd ring, substans tiallyas shown and described.

A piston provided in radial recesses or pockets thereof with spring-pressed blocks or 5 studs, aiing reversely beveled on its outer sur face and fitted in aperipheral groove of the piston, and paekingningstted on s'aid beveled -ring and beveled to conformvt'o the same, substantially as shown and described.

ro 3. In a piston, the combination, with packingfrings tted in the periphery thereof, of a segmental ring behind said packing-rings, a

series of studs or bloeksin radalpockets or recesses in the piston, and spiral" springs on the shanks of said studs or blocks', substan- 15 tially as shown and described.

In testimony that we ela-im the foregoing as our invention we have signed our names, in presence of two Witnesses, this 14th day of October, 1886.. 

